[1.7.10] How to set an entity to be invincible based on a boolean value

Hi everyone,

I have an entity which changes its model to become the player when my player becomes this entity. Essentially swapping places where the entity gets the players model and the player gets the entities model (among other things). All of this works fine and the entity knows when to morph into the player based on a boolean that is updated by the player. This boolean is true when my entity is in its morphed state (it is the player). I want to make the entity invincible while this boolean is true and not invincible when the boolean is false. Seems pretty simple  but I am not sure what a good way to go about this would be. Any ideas.

Thornack